从福建分离的广东赛葵曲叶病毒的分子特征(英文)

Molecular Characterization of Malvastrum leaf curl Guangdong virus Isolated from Fujian,China

从中国福建省表现曲叶和脉突症状的赛葵上分离到病毒分离物FJ1～FJ6。利用菜豆金色花叶病毒属病毒的特异性简并引物PA／PB，在所有6个分离物中都分离到了约500bp长度的病毒部分DNA片段。这些DNA片段与已报道的广东赛葵曲叶病毒（Malvastrum leaf curl Guangdong virus，MLCuGdV）的核苷酸序列同源性高达90％-93％。随机挑选FJ3分离物进行全基因组DNA的克隆测序。结果表明，FJ3 DNA全长2765个核苷酸，具有典型的双生病毒科病毒的基因组结构特征，与MLCuGdV的同源性为92．9％，表明FJ3是MLCuGdV的一个分离物。系统进化分析表明，除了MLCuGdV，FJ3与其它赛葵上分离到的双生病毒的亲缘关系都较远，而与分离自中国南方番木瓜上的双生病毒聚成簇，有较近的亲缘关系。进一步比较分析各蛋白编码的氨基酸序列发现，FJ3可能是一个种间重组分子，它可能是由中国番木瓜曲叶病毒或广东番木瓜曲叶病毒和另外的未知病毒重组产生的。

Six virus isolates （FJI -FJ6） were obtained from Malvastrurn coromandelianurn plants showing leaf curl and vein banding symptoms in Fujian Province, China. Partial viral DNA fragment, approximately 500 bp long was amplified from all the six isolates by PCR using the degenerate primer pair PA/PB, specific for begomoviruses （ Family Geminiviridae）. The partial fragments shared the highest nucleotide sequence identity （90%-93%） with the previously reported Malvastrum leaf curl Guangdong virus （MLCuGdV）. Isolate FJ3 was randomly selected for cloning and sequencing the complete viral genomic DNA. FJ3 complete DNA was 2 765 nucleotides long with all the characteristic features of a begomovirus genomic organization and shared 93% nucleotide sequence identity with the previously described MLCuGdV isolate from Guangdong, and was therefore considered to be an isolate of MLCuGdV. In phylogenetic analysis, FJ3 showed low affinity to other reported Malvastrum-infecting begomoviruses except MLCuGdV. Instead, it showed high affinity and clusters together with papaya-infecting begomoviruses isolated from the same agro-ecological zone of South China. Further comparisons of amino acid sequences of encoded proteins indicate that FJ3 is a chimeric molecule that has arisen by interspecific recombination between Papaya leaf curl China virus or Papaya leaf curl Guangdong virus as the major parent and other unidentified ancestors as minor parents.